I could fatigue you could fatigue he could fatigue we could fatigue you could fatigue they could fatigue
V-ing form
I could be fatiguing you could be fatiguing he could be fatiguing we could be fatiguing you could be fatiguing they could be fatiguing
Perfect
I could have fatigued you could have fatigued he could have fatigued we could have fatigued you could have fatigued they could have fatigued
V-ing perfect
I could have been fatiguing you could have been fatiguing he could have been fatiguing we could have been fatiguing you could have been fatiguing they could have been fatiguing
Negation
Simple form
I couldn't fatigue you couldn't fatigue he couldn't fatigue we couldn't fatigue you couldn't fatigue they couldn't fatigue
V-ing form
I couldn't be fatiguing you couldn't be fatiguing he couldn't be fatiguing we couldn't be fatiguing you couldn't be fatiguing they couldn't be fatiguing
Perfect
I couldn't have fatigued you couldn't have fatigued he couldn't have fatigued we couldn't have fatigued you couldn't have fatigued they couldn't have fatigued
V-ing perfect
I couldn't have been fatiguing you couldn't have been fatiguing he couldn't have been fatiguing we couldn't have been fatiguing you couldn't have been fatiguing they couldn't have been fatiguing
Interrogative form
Simple form
could I fatigue? could you fatigue? could he fatigue? could we fatigue? could you fatigue? could they fatigue?
V-ing form
could I be fatiguing? could you be fatiguing? could he be fatiguing? could we be fatiguing? could you be fatiguing? could they be fatiguing?
Perfect
could I have fatigued? could you have fatigued? could he have fatigued? could we have fatigued? could you have fatigued? could they have fatigued?
V-ing perfect
could I have been fatiguing? could you have been fatiguing? could he have been fatiguing? could we have been fatiguing? could you have been fatiguing? could they have been fatiguing?
Interro-negative form
Simple form
couldn't I fatigue? couldn't you fatigue? couldn't he fatigue? couldn't we fatigue? couldn't you fatigue? couldn't they fatigue?
V-ing form
couldn't I be fatiguing? couldn't you be fatiguing? couldn't he be fatiguing? couldn't we be fatiguing? couldn't you be fatiguing? couldn't they be fatiguing?
Perfect
couldn't I have fatigued? couldn't you have fatigued? couldn't he have fatigued? couldn't we have fatigued? couldn't you have fatigued? couldn't they have fatigued?
V-ing perfect
couldn't I have been fatiguing? couldn't you have been fatiguing? couldn't he have been fatiguing? couldn't we have been fatiguing? couldn't you have been fatiguing? couldn't they have been fatiguing?